LESSON 1: BEINGS MODEL

• BEINGS MODEL: Biologic and Behavioral factors

  The risk for particular diseases may be influenced by gender, age, weight, bone density, and other biologic factors.
• In addition, human behavior is a central factor in health and disease. Cigarette smoking is an obvious example of a behavioral risk factor.
• Increasing attention has focused on the rapid increase in overweight and obesity in the U.S. population over the past two decades.
• Obesity and overweight have negative health effects, par- ticularly by reducing the age at onset of, and increasing the prevalence of, type 2 diabetes.
• In each of these cases, as in cigarette smoking and HIV infection, changes in behavior could prevent the unto- ward outcomes.
• Epidemiologists are frequently the first professionals to respond to an apparent outbreak of new health problems, such as legionnaires’ disease and Lyme disease, which involve important environmental factors.
• In their investigations, epidemiologists describe the patterns of the disease in the affected population, develop and test hypotheses about causal factors, and introduce methods to prevent further cases of disease.
• Only later, after the identifica- tion of Legionella pneumophila, was it discovered that this small bacterium thrives in air-conditioning cooling towers and warm-water systems.
• By 1977 it was clear that the disease, then known as Lyme disease, was spread by Ixodes ticks, opening the way for more specific prevention and research. Not until 1982, however, was the causative agent, Borrelia burgdorferi, discovered and shown to be spread by the Ixodes tick.
• Smallpox is the first infectious disease known to have been eradicated from the globe
• Smallpox eradication was possible because vaccination against the disease conferred individual immunity and produced herd immunity.
• Herd immunity results when a vaccine diminishes an immunized person’s ability to spread a disease, leading to reduced disease transmission.
• immunodeficiency also may be caused by genetic abnormalities and other factors.
• Transient immune deficiency has been noted after some infections (e.g., measles) and after the administration of certain vaccines (e.g., live measles vaccine).
• Based on cross-cultural studies, Burkitt observed that many of the diseases commonly seen in the United States, such as diabetes and hypertension, were rarely encountered in indigenous populations of tropical Africa
• genetic inheritance of individuals interacts with diet and environment in complex ways
• genetic epidemiology- distribution of normal and abnormal genes in a population, and whether or not these are in equilibrium.
• Heritability refers to the contribution of genes relative to all determinants of disease.
• Genetic screening is important for identifying problems in newborns, such as phenylketonuria and congenital hypothyroidism, for which therapy can be extremely beneficial if instituted early enough.
• Screening for susceptibility genes undoubtedly will increase in the future
• Medical care services may be beneficial to health but also can be dangerous. One of the important tasks of epidemiologists is to determine the benefits and hazards of medical care in different settings.
• Iatrogenic disease occurs when a disease is induced inadvertently by treatment or during a diagnostic procedure.
• This is an example of Iatrogenic disease: annual screening mammography over a 10-year period will have at least one mammogram inter- preted as suspicious for breast cancer and will therefore be advised to undergo additional testing, even though they do not have cancer.
• This is an example of social and spiritual factors: association of religious faith with generally better health and found that strong religious faith was associated with better health and quality of life. The effects of meditation and massage on quality of life in patients with advanced disease (e.g., AIDS) have also been studied.